O2 sensor or vacum leak?

[adrian222]

I have a 850GLT 96 (157k)
My check engine light is on due to a PO137 code (low voltage of rear o2 sensor)
I did some research and I find out that you can get lean O2 sensor codes with a vacuum leak. For example a bad intake manifold gasket can flash these codes. QUESTION IS:
Is it true that if you got your CEL(check engine light) at idle or low speeds you may not need new O2 sensors and the problem is the vacum leak not the sensor?

But if you get CEL at high speed the computer can easily add enough fuel to prevent a lean condition due to a vacuum leak. Thus, his problem is likely due to bad O2 sensors. The point being if you got your CEL at idle or low speeds you may not need new O2 sensors.

[matthew1]

I have no clue .

But I can recommend looking at your engine bay for cracked vaccum tubes or vacuum tube elbows, or for tubes that have pulled off from the nipple. Eliminate the easiest cause first, then move toward more expensive/time consuming solutions.